ABSTRACT
Mutations in the receptor tyrosine kinase (RTK/RAS) signalling pathway frequently provide a proliferative signal in myeloid malignancies. However, the role of RASSF1A, SHP-1 and SOCS-1, negative regulators of RTK/RAS signalling, has not been extensively investigated in the myelodysplastic syndromes (MDS) or acute myeloid leukaemia (AML). This study employed methylation-specific polymerase chain reaction (MS-PCR) to determine if aberrant promotor methylation of RASSF1A, SHP-1 and SOCS-1 is involved in the pathogenesis of myeloid malignancies. Patients with MDS (n = 107), AML (n = 154) and juvenile myelomonocytic leukaemia (JMML, n = 5) were investigated, together with 15 normal controls. Primers were located in the promotor region of each gene as well as within exon 2 of SOCS-1. Methylation of RASSF1A was found in five of 55 (9%) MDS cases, but not in any of 57 AML cases studied. RASSF1A methylation was present in one case (20%) of JMML. SHP-1 methylation was present in 13 of 121 (11%) AML cases but was not found in MDS or JMML. SOCS-1 promoter methylation was present in eight of 74 (11%) MDS patients but was not seen in JMML or AML. Importantly, RAS mutations and RASSF1A and SOCS-1 methylation were mutually exclusive indicating that approximately 30% of MDS cases had a defect of the RTK/RAS pathway and its negative regulation. Finally, SOCS-1 exon 2 methylation may not be pathogenetically relevant, since it was detected in samples from normal individuals and did not correlate with promotor methylation.
Subject(s)
DNA Methylation , Myelodysplastic Syndromes/genetics , Neoplasm Proteins/genetics , Acute Disease , DNA, Neoplasm/genetics , Humans , Intracellular Signaling Peptides and Proteins/genetics , Leukemia, Myeloid/genetics , Polymerase Chain Reaction/methods , Protein Tyrosine Phosphatase, Non-Receptor Type 6 , Protein Tyrosine Phosphatases/genetics , Repressor Proteins/genetics , Sensitivity and Specificity , Sequence Analysis, DNA/methods , Suppressor of Cytokine Signaling 1 Protein , Suppressor of Cytokine Signaling Proteins , Tumor Suppressor Proteins/geneticsABSTRACT
In acute myeloid leukemia (AML), further prognostic determinants are required in addition to cytogenetics to predict patients at increased risk of relapse. Recent studies have indicated that an internal tandem duplication (ITD) in the FLT3 gene may adversely affect clinical outcome. This study evaluated the impact of a FLT3/ITD mutation on outcome in 854 patients, mostly 60 years of age or younger, treated in the United Kingdom Medical Research Council (MRC) AML trials. An FLT3/ITD mutation was present in 27% of the patients and was associated with leukocytosis and a high percentage of bone marrow blast cells (P <.001 for both). It had a borderline association with a lower complete remission rate (P =.05) and a higher induction death rate (P =.04), and was associated with increased relapse risk (RR), adverse disease-free survival (DFS), event-free survival (EFS), and overall survival (OS) (P <.001 for all). In multivariate analysis, presence of a mutation was the most significant prognostic factor predicting RR and DFS (P <.0001) and was still significant for OS (P =.009) and EFS (P =.002). There was no evidence that the relative effect of a FLT3/ITD differed between the cytogenetic risk groups. More than one mutation was detected in 23% of FLT3/ITD(+) patients and was associated with worse OS (P =.04) and EFS (P =.07). Biallelic disease or partial/complete loss of wild-type alleles was present in 10% of FLT3/ITD(+) patients. The suggestion is made that detection of a FLT3/ITD should be included as a routine test at diagnosis and evaluated for therapeutic management.
Subject(s)
Gene Duplication , Leukemia, Myeloid/drug therapy , Leukemia, Myeloid/genetics , Proto-Oncogene Proteins/genetics , Receptor Protein-Tyrosine Kinases/genetics , Acute Disease , Adolescent , Adult , Cytogenetic Analysis , Disease-Free Survival , Female , Follow-Up Studies , Humans , Leukemia, Myeloid/diagnosis , Leukemia, Myeloid/mortality , Male , Middle Aged , Neoplasm Recurrence, Local , Polymerase Chain Reaction , Prognosis , Reproducibility of Results , Risk Factors , Treatment Outcome , fms-Like Tyrosine Kinase 3ABSTRACT
It is suggested that monocytes in patients with chronic myelomonocytic leukaemia (CMML) or chronic myeloid leukaemia (CML) with monocytosis have morphological/functional abnormalities which cause inaccurate counting in automated analysers. In this study, monocytes in 21 normal and 14 CMML blood samples were subjected to morphological analysis and were counted by the manual reference method, three automated analysers and esterase staining. Morphological analysis showed no significant difference between control and CMML monocytes. The alpha-naphthyl acetate esterase scores, a measure of monocyte function, showed a reduction of 40% in CMML monocytes compared to controls. Counts by analysers showed that the Sysmex NE 8000 was the least accurate for CMML monocyte counts and that the Coulter STK-S and Sysmex SE 9000 gave results closer to the manually counted standards.
